Rapid Research Review: Study Types

Case-Control (“What happened?”)

Compares a group with a disease to a group without disease.  This study can calculate an odds ratio.

Advantages: many exposures can be studied and is useful for rare disorders.

Disadvantages: confounding factors and the potential for recall/selection bias.

Cohort (“What will happen?”)

Compares a group with an exposure/risk factor to a group without exposure. This study can calculate a relative risk.

Advantages: ethically safe, timing and directionality of events can be established

Disadvantages: blinding is difficult; no randomization; controls may be difficult to identify

Cross-Sectional Study (“What is happening?”)

Collects data from a group of people to assess frequency of disease and related risk factors at a particular point in time. This study can help calculate disease prevalence.

Advantages: ethically safe

Disadvantages: potential recall or Neyman bias; association can be established but not causality